Ware

Upon casting this spell, you become unnaturally aware of your surroundings. For the duration, you're aware if anyone is watching you that you don't already know. For you to sense something watching you, it must be actively watching you purposefully, such as spying, scrying and not casually looking in your direction.

You can't learn any information about what or who's watching you this way, only if you're being watched or not.